<?php
	session_start();
	
	if (!isset($_SESSION['username'])) {
?>
		<form action="">
			Username: <input id="username" type="text"/>
			Password: <input id="password" type="password"/>
			<input type="button" value="Login" onclick="login();" />
		</form>
<?php
	} else {
		echo "Logged in!";
		exit;
	}
?>